{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE CPP #-}

module Data.Validity.Path where

import Data.Validity

import Path
import Path.Internal

import Data.List (isInfixOf, isSuffixOf)

import qualified System.FilePath as FilePath


-- | An absolute path to a file is valid if:
--
-- * Its path is an absolute path
-- * Its path has no trailing path separators
-- * Its path is valid according to 'System.FilePath's definition.
-- * Its path does not end in '/.'
#if MIN_VERSION_path(0,6,0)
-- * Its path is not '.'
#endif
-- * Its path does not contain '..'.
-- * Parsing the path and rendering it again results in the same path.
instance Validity (Path Abs File) where
    validate p@(Path fp) =
        mconcat
            [ declare "The path is absolute." $ FilePath.isAbsolute fp
            , declare "The path has no trailing path separator." $
              not (FilePath.hasTrailingPathSeparator fp)
            , declare "System.FilePath considers the path valid." $
              FilePath.isValid fp
            , declare "The path does not end in /." $ not ("/." `isSuffixOf` fp)
#if MIN_VERSION_path(0,6,0)
            , declare "The path does not equal \".\"" $ fp /= "."
#endif
            , declare "The path does not contain '..'." $ not (".." `isInfixOf` fp)
            , declare "The path can be identically parsed as an absolute file path." $
              parseAbsFile fp == Just p
            ]

-- | A relative path to a file is valid if:
--
-- * Its path is a relative path
-- * Its path does not have a trailing path separator
-- * Its path is valid according to 'System.FilePath's definition.
-- * Its path is not '.'
-- * Its path is not empty
#if MIN_VERSION_path(0,6,0)
-- * Its path does not end in '/.'
#endif
-- * Its path is not '.'
-- * Its path does not contain '..'.
-- * Parsing the path and rendering it again results in the same path.
instance Validity (Path Rel File) where
    validate p@(Path fp) =
        mconcat
            [ declare "The path is relative." $ FilePath.isRelative fp
            , declare "The path has no trailing path separator." $
              not (FilePath.hasTrailingPathSeparator fp)
            , declare "System.FilePath considers the path valid." $
              FilePath.isValid fp
            , declare "The path does not equal \".\"" $ fp /= "."
            , declare "The path is not empty" $ not (null fp)
#if MIN_VERSION_path(0,6,0)
            , declare "The path does not end in /." $ not ("/." `isSuffixOf` fp)
#endif
            , declare "The path does not contain '..'." $ not (".." `isInfixOf` fp)
            , declare "The path can be identically parsed as a relative file path." $
              parseRelFile fp == Just p
            ]

-- | An absolute path to a directory is valid if:
--
-- * Its path is an absolute path
-- * Its path has a trailing path separator
-- * Its path is valid according to 'System.FilePath's definition.
-- * Its path does not contain '..'.
-- * Parsing the path and rendering it again results in the same path.
instance Validity (Path Abs Dir) where
    validate p@(Path fp) =
        mconcat
            [ declare "The path is absolute." $ FilePath.isAbsolute fp
            , declare "The path has a trailing path separator." $
              FilePath.hasTrailingPathSeparator fp
            , declare "System.FilePath considers the path valid." $
              FilePath.isValid fp
            , declare "The path does not contain '..'." $ not (".." `isInfixOf` fp)
            , declare "The path can be identically parsed as an absolute directory path." $
              parseAbsDir fp == Just p
            ]

-- | A relative path to a directory is valid if:
--
-- * Its path is a relative path
-- * Its path has a trailing path separator
-- * Its path is valid according to 'System.FilePath's definition.
#if MIN_VERSION_path(0,6,0)
#else
-- * Its path is not '.'
#endif
-- * Its path does not contain '..'.
-- * Parsing the path and rendering it again results in the same path.
instance Validity (Path Rel Dir) where
    validate p@(Path fp) =
        mconcat
            [ declare "The path is relative." $ FilePath.isRelative fp
            , declare "The path has a trailing path separator." $
              FilePath.hasTrailingPathSeparator fp
            , declare "System.FilePath considers the path valid." $
              FilePath.isValid fp
            , declare "The path is not empty." $ not (null fp)
#if MIN_VERSION_path(0,6,0)
#else
            , declare "The path does not equal \".\"" $ fp /= "."
#endif
            , declare "The path does not contain '..'." $ not (".." `isInfixOf` fp)
            , declare "The path can be identically parsed as a relative directory path." $
              parseRelDir fp == Just p
            ]